Python – Sympy Polygon.cut_section() 方法

在 Sympy 中，函数Polygon.cut_section ()用于 获得分别位于相交线上方和下方的两个多边形段（多边形的两部分）的元组。它只是返回与线相交的多边形的两个部分。在线上方或下方不存在多边形时返回 None。

Syntax: Polygon.cut_section(line)

Returns: upper_polygon, lower_polygon: Polygon objects or None
 upper_polygon: is the polygon that lies above the given line
 lower_polygon: is the polygon that lies below the given line
 None: when no polygon exists above the line or below the line
 
Raises: 
 ValueError: When the line does not intersect the polygon

示例 #1：

Python3

# import sympy import Point, Polygon, Line
from sympy import Point, Polygon, Line
  
# creating points using Point()
p1, p2, p3, p4 = map(Point, [(0, 2), (0, 0), (1, 0), (1, 2)])
  
# creating polygon using Polygon()
poly = Polygon(p1, p2, p3, p4)
  
# using cut_section()
cutSection = poly.cut_section(Line((0, 1), slope = 0))
  
print(cutSection)

输出：

(Polygon(Point2D(0, 2), Point2D(0, 1), Point2D(1, 1), Point2D(1, 2)), 
 Polygon(Point2D(0, 1), Point2D(0, 0), Point2D(1, 0), Point2D(1, 1)))

示例 #2：

Python3

# import sympy import Point, Polygon, Line
from sympy import Point, Polygon, Line
  
# creating points using Point()
p1, p2, p3, p4 = map(Point, [(0, 2), (0, 0), (1, 0), (1, 2)])
  
# creating polygon using Polygon()
poly = Polygon(p1, p2, p3, p4)
  
# using cut_section()
cutSection = poly.cut_section(Line((0, 1), slope = 1))
  
print(cutSection)

输出：

(Triangle(Point2D(0, 2), Point2D(0, 1), Point2D(1, 2)), 
 Polygon(Point2D(0, 1), Point2D(0, 0), Point2D(1, 0), Point2D(1, 2)))